#include "fastmath.h"
#include "common.h"

#define FAST_SIN_TABLE_SIZE 512

AT_ITCM_SECTION_INIT(float fast_sqrti(float x))
{
    union {
        unsigned int i;
        float f;
    } l2f;
    l2f.f = x;
    l2f.i = 0x5F1F1412 - (l2f.i >> 1);
    return l2f.f * (1.69000231f - 0.714158168f * x * l2f.f * l2f.f);
}
AT_ITCM_SECTION_INIT(float fast_sqrt(float x))
{
    return x * fast_sqrti(x);
}

const float sinTable[FAST_SIN_TABLE_SIZE + 1] = {
    0.00000000f, 0.01227154f, 0.02454123f, 0.03680722f, 0.04906767f, 0.06132074f,
    0.07356456f, 0.08579731f, 0.09801714f, 0.11022221f, 0.12241068f, 0.13458071f,
    0.14673047f, 0.15885814f, 0.17096189f, 0.18303989f, 0.19509032f, 0.20711138f,
    0.21910124f, 0.23105811f, 0.24298018f, 0.25486566f, 0.26671276f, 0.27851969f,
    0.29028468f, 0.30200595f, 0.31368174f, 0.32531029f, 0.33688985f, 0.34841868f,
    0.35989504f, 0.37131719f, 0.38268343f, 0.39399204f, 0.40524131f, 0.41642956f,
    0.42755509f, 0.43861624f, 0.44961133f, 0.46053871f, 0.47139674f, 0.48218377f,
    0.49289819f, 0.50353838f, 0.51410274f, 0.52458968f, 0.53499762f, 0.54532499f,
    0.55557023f, 0.56573181f, 0.57580819f, 0.58579786f, 0.59569930f, 0.60551104f,
    0.61523159f, 0.62485949f, 0.63439328f, 0.64383154f, 0.65317284f, 0.66241578f,
    0.67155895f, 0.68060100f, 0.68954054f, 0.69837625f, 0.70710678f, 0.71573083f,
    0.72424708f, 0.73265427f, 0.74095113f, 0.74913639f, 0.75720885f, 0.76516727f,
    0.77301045f, 0.78073723f, 0.78834643f, 0.79583690f, 0.80320753f, 0.81045720f,
    0.81758481f, 0.82458930f, 0.83146961f, 0.83822471f, 0.84485357f, 0.85135519f,
    0.85772861f, 0.86397286f, 0.87008699f, 0.87607009f, 0.88192126f, 0.88763962f,
    0.89322430f, 0.89867447f, 0.90398929f, 0.90916798f, 0.91420976f, 0.91911385f,
    0.92387953f, 0.92850608f, 0.93299280f, 0.93733901f, 0.94154407f, 0.94560733f,
    0.94952818f, 0.95330604f, 0.95694034f, 0.96043052f, 0.96377607f, 0.96697647f,
    0.97003125f, 0.97293995f, 0.97570213f, 0.97831737f, 0.98078528f, 0.98310549f,
    0.98527764f, 0.98730142f, 0.98917651f, 0.99090264f, 0.99247953f, 0.99390697f,
    0.99518473f, 0.99631261f, 0.99729046f, 0.99811811f, 0.99879546f, 0.99932238f,
    0.99969882f, 0.99992470f, 1.00000000f, 0.99992470f, 0.99969882f, 0.99932238f,
    0.99879546f, 0.99811811f, 0.99729046f, 0.99631261f, 0.99518473f, 0.99390697f,
    0.99247953f, 0.99090264f, 0.98917651f, 0.98730142f, 0.98527764f, 0.98310549f,
    0.98078528f, 0.97831737f, 0.97570213f, 0.97293995f, 0.97003125f, 0.96697647f,
    0.96377607f, 0.96043052f, 0.95694034f, 0.95330604f, 0.94952818f, 0.94560733f,
    0.94154407f, 0.93733901f, 0.93299280f, 0.92850608f, 0.92387953f, 0.91911385f,
    0.91420976f, 0.90916798f, 0.90398929f, 0.89867447f, 0.89322430f, 0.88763962f,
    0.88192126f, 0.87607009f, 0.87008699f, 0.86397286f, 0.85772861f, 0.85135519f,
    0.84485357f, 0.83822471f, 0.83146961f, 0.82458930f, 0.81758481f, 0.81045720f,
    0.80320753f, 0.79583690f, 0.78834643f, 0.78073723f, 0.77301045f, 0.76516727f,
    0.75720885f, 0.74913639f, 0.74095113f, 0.73265427f, 0.72424708f, 0.71573083f,
    0.70710678f, 0.69837625f, 0.68954054f, 0.68060100f, 0.67155895f, 0.66241578f,
    0.65317284f, 0.64383154f, 0.63439328f, 0.62485949f, 0.61523159f, 0.60551104f,
    0.59569930f, 0.58579786f, 0.57580819f, 0.56573181f, 0.55557023f, 0.54532499f,
    0.53499762f, 0.52458968f, 0.51410274f, 0.50353838f, 0.49289819f, 0.48218377f,
    0.47139674f, 0.46053871f, 0.44961133f, 0.43861624f, 0.42755509f, 0.41642956f,
    0.40524131f, 0.39399204f, 0.38268343f, 0.37131719f, 0.35989504f, 0.34841868f,
    0.33688985f, 0.32531029f, 0.31368174f, 0.30200595f, 0.29028468f, 0.27851969f,
    0.26671276f, 0.25486566f, 0.24298018f, 0.23105811f, 0.21910124f, 0.20711138f,
    0.19509032f, 0.18303989f, 0.17096189f, 0.15885814f, 0.14673047f, 0.13458071f,
    0.12241068f, 0.11022221f, 0.09801714f, 0.08579731f, 0.07356456f, 0.06132074f,
    0.04906767f, 0.03680722f, 0.02454123f, 0.01227154f, 0.00000000f, -0.01227154f,
    -0.02454123f, -0.03680722f, -0.04906767f, -0.06132074f, -0.07356456f,
    -0.08579731f, -0.09801714f, -0.11022221f, -0.12241068f, -0.13458071f,
    -0.14673047f, -0.15885814f, -0.17096189f, -0.18303989f, -0.19509032f,
    -0.20711138f, -0.21910124f, -0.23105811f, -0.24298018f, -0.25486566f,
    -0.26671276f, -0.27851969f, -0.29028468f, -0.30200595f, -0.31368174f,
    -0.32531029f, -0.33688985f, -0.34841868f, -0.35989504f, -0.37131719f,
    -0.38268343f, -0.39399204f, -0.40524131f, -0.41642956f, -0.42755509f,
    -0.43861624f, -0.44961133f, -0.46053871f, -0.47139674f, -0.48218377f,
    -0.49289819f, -0.50353838f, -0.51410274f, -0.52458968f, -0.53499762f,
    -0.54532499f, -0.55557023f, -0.56573181f, -0.57580819f, -0.58579786f,
    -0.59569930f, -0.60551104f, -0.61523159f, -0.62485949f, -0.63439328f,
    -0.64383154f, -0.65317284f, -0.66241578f, -0.67155895f, -0.68060100f,
    -0.68954054f, -0.69837625f, -0.70710678f, -0.71573083f, -0.72424708f,
    -0.73265427f, -0.74095113f, -0.74913639f, -0.75720885f, -0.76516727f,
    -0.77301045f, -0.78073723f, -0.78834643f, -0.79583690f, -0.80320753f,
    -0.81045720f, -0.81758481f, -0.82458930f, -0.83146961f, -0.83822471f,
    -0.84485357f, -0.85135519f, -0.85772861f, -0.86397286f, -0.87008699f,
    -0.87607009f, -0.88192126f, -0.88763962f, -0.89322430f, -0.89867447f,
    -0.90398929f, -0.90916798f, -0.91420976f, -0.91911385f, -0.92387953f,
    -0.92850608f, -0.93299280f, -0.93733901f, -0.94154407f, -0.94560733f,
    -0.94952818f, -0.95330604f, -0.95694034f, -0.96043052f, -0.96377607f,
    -0.96697647f, -0.97003125f, -0.97293995f, -0.97570213f, -0.97831737f,
    -0.98078528f, -0.98310549f, -0.98527764f, -0.98730142f, -0.98917651f,
    -0.99090264f, -0.99247953f, -0.99390697f, -0.99518473f, -0.99631261f,
    -0.99729046f, -0.99811811f, -0.99879546f, -0.99932238f, -0.99969882f,
    -0.99992470f, -1.00000000f, -0.99992470f, -0.99969882f, -0.99932238f,
    -0.99879546f, -0.99811811f, -0.99729046f, -0.99631261f, -0.99518473f,
    -0.99390697f, -0.99247953f, -0.99090264f, -0.98917651f, -0.98730142f,
    -0.98527764f, -0.98310549f, -0.98078528f, -0.97831737f, -0.97570213f,
    -0.97293995f, -0.97003125f, -0.96697647f, -0.96377607f, -0.96043052f,
    -0.95694034f, -0.95330604f, -0.94952818f, -0.94560733f, -0.94154407f,
    -0.93733901f, -0.93299280f, -0.92850608f, -0.92387953f, -0.91911385f,
    -0.91420976f, -0.90916798f, -0.90398929f, -0.89867447f, -0.89322430f,
    -0.88763962f, -0.88192126f, -0.87607009f, -0.87008699f, -0.86397286f,
    -0.85772861f, -0.85135519f, -0.84485357f, -0.83822471f, -0.83146961f,
    -0.82458930f, -0.81758481f, -0.81045720f, -0.80320753f, -0.79583690f,
    -0.78834643f, -0.78073723f, -0.77301045f, -0.76516727f, -0.75720885f,
    -0.74913639f, -0.74095113f, -0.73265427f, -0.72424708f, -0.71573083f,
    -0.70710678f, -0.69837625f, -0.68954054f, -0.68060100f, -0.67155895f,
    -0.66241578f, -0.65317284f, -0.64383154f, -0.63439328f, -0.62485949f,
    -0.61523159f, -0.60551104f, -0.59569930f, -0.58579786f, -0.57580819f,
    -0.56573181f, -0.55557023f, -0.54532499f, -0.53499762f, -0.52458968f,
    -0.51410274f, -0.50353838f, -0.49289819f, -0.48218377f, -0.47139674f,
    -0.46053871f, -0.44961133f, -0.43861624f, -0.42755509f, -0.41642956f,
    -0.40524131f, -0.39399204f, -0.38268343f, -0.37131719f, -0.35989504f,
    -0.34841868f, -0.33688985f, -0.32531029f, -0.31368174f, -0.30200595f,
    -0.29028468f, -0.27851969f, -0.26671276f, -0.25486566f, -0.24298018f,
    -0.23105811f, -0.21910124f, -0.20711138f, -0.19509032f, -0.18303989f,
    -0.17096189f, -0.15885814f, -0.14673047f, -0.13458071f, -0.12241068f,
    -0.11022221f, -0.09801714f, -0.08579731f, -0.07356456f, -0.06132074f,
    -0.04906767f, -0.03680722f, -0.02454123f, -0.01227154f, -0.00000000f
};

AT_ITCM_SECTION_INIT(float fast_sin(float x))
{
    float sinVal, fract, in; // Temporary variables for input, output
    unsigned short index; // Index variable
    float a, b; 
    int n;
    float findex;
    in = x * 0.159154943092f;

    // Calculation of floor value of input
    n = (int) in;

    // Make negative values towards -infinity
    if(x < 0.0f) {
        n--;
    }

    // Map input value to [0 1]
    in = in - (float) n;

    // Calculation of index of the table
    findex = (float) FAST_SIN_TABLE_SIZE * in;
    index = ((unsigned short)findex) & 0x1ff;

    // fractional value calculation
    fract = findex - (float) index;

    // Read two nearest values of input value from the sin table
    a = sinTable[index];
    b = sinTable[index+1];

    // Linear interpolation process
    sinVal = (1.0f-fract)*a + fract*b;

    // Return the output value
    return (sinVal);
}

AT_ITCM_SECTION_INIT(float fast_cos(float x))
{
    float cosVal, fract, in; // Temporary variables for input, output
    unsigned short index; // Index variable
    float a, b; // Two nearest output values
    int n;
    float findex;

    // input x is in radians
    // Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi, add 0.25 (pi/2) to read sine table
    in = x * 0.159154943092f + 0.25f;

    // Calculation of floor value of input
    n = (int) in;

    // Make negative values towards -infinity
    if(in < 0.0f) {
        n--;
    }

    // Map input value to [0 1]
    in = in - (float) n;

    // Calculation of index of the table
    findex = (float) FAST_SIN_TABLE_SIZE * in;
    index = ((unsigned short)findex) & 0x1ff;

    // fractional value calculation
    fract = findex - (float) index;

    // Read two nearest values of input value from the cos table
    a = sinTable[index];
    b = sinTable[index+1];

    // Linear interpolation process
    cosVal = (1.0f-fract)*a + fract*b;

    // Return the output value
    return (cosVal);
}

AT_ITCM_SECTION_INIT(float fast_tan(float x))
{
    long n;
    float xn;
    float f, g;
    float x_int, x_fract;
    float result;
    float xnum, xden;

    if ((x > (float)X_MAX) || (x < (float)-X_MAX)) {
        return (float)0.0;
    }

    x_int = (float)((long)(x));
    x_fract = x - x_int;

    g = (float)0.5;
    if (x <= (float)0.0) {
        g = -g;
    }
    n = (long)(x * (float)INV_PI_2 + g);
    xn = (float)(n);

    f = x_int - xn * PI_2_C1;
    f = f + x_fract;
    f = f - xn * PI_2_C2;
    f = f - xn * PI_2_C3;

    if (f < (float)0.0) {
        g = -f;
    }
    else {
        g = f;
    }
    if (g < (float)EPS_FLOAT) {
        if (n & 0x0001) {
            result = -1.0f / f;
        }
        else {
            result = f;
        }
        return result;
    }

    g = f * f;
    xnum = g * TANP_COEF2;
    xnum = xnum + TANP_COEF1;
    xnum = xnum * g;
    xnum = xnum * f;
    xnum = xnum + f;

    xden = g * TANQ_COEF2;
    xden = xden + TANQ_COEF1;
    xden = xden * g;
    xden = xden + TANQ_COEF0;

    if (n & 0x0001) {
        result = xnum;
        xnum = -xden;
        xden = result;
    }
    result = xnum / xden;
    return result;
}

AT_ITCM_SECTION_INIT(float fast_asin(float x))
{
    float y, g;
    float num, den, result;
    long i;
    float sign = 1.0;

    y = x;
    if (y < (float)0.0) {
        y = -y;
        sign = -sign;
    }

    if (y > (float)0.5) {
        i = 1;
        if (y > (float)1.0) {
            result = 0.0;
            return result;
        }
        g = (1.0f - y) * 0.5f;
        y = -2.0f * fast_sqrt(g);
    }
    else {
        i = 0;
        if (y < (float)EPS_FLOAT) {
            result = y;
            if (sign < (float)0.0) {
                result = -result;
            }
            return result;
        }
        g = y * y;
    }
    num = ((ASINP_COEF3 * g + ASINP_COEF2) * g + ASINP_COEF1) * g;
    den = ((g + ASINQ_COEF2) * g + ASINQ_COEF1) * g + ASINQ_COEF0;
    result = num / den;
    result = result * y + y;
    if (i == 1) {
        result = result + (float)PI_2;
    }
    if (sign < (float)0.0) {
        result = -result;
    }
    return result;
}

AT_ITCM_SECTION_INIT(float fast_atan2(float y, float x))
{
    float f, g;
    float num, den;
    float result;
    int n;

    static const float a[4] = {0, (float)PI_6, (float)PI_2, (float)PI_3};

    if (x == (float)0.0) {
        if (y == (float)0.0) {
            result = 0.0;
            return result;
        }

        result = (float)PI_2;
        if (y > (float)0.0) {
            return result;
        }
        if (y < (float)0.0) {
            result = -result;
            return result;
        }
    }
    n = 0;
    num = y;
    den = x;

    if (num < (float)0.0) {
        num = -num;
    }
    if (den < (float)0.0) {
        den = -den;
    }
    if (num > den) {
        f = den;
        den = num;
        num = f;
        n = 2;
    }
    f = num / den;

    if (f > (float)TWO_MINUS_ROOT3) {
        num = f * (float)SQRT3_MINUS_1 - 1.0f + f;
        den = (float)SQRT3 + f;
        f = num / den;
        n = n + 1;
    }

    g = f;
    if (g < (float)0.0) {
        g = -g;
    }

    if (g < (float)EPS_FLOAT) {
        result = f;
    }
    else {
        g = f * f;
        num = (ATANP_COEF1 * g + ATANP_COEF0) * g;
        den = (g + ATANQ_COEF1) * g + ATANQ_COEF0;
        result = num / den;
        result = result * f + f;
    }
    if (n > 1) {
        result = -result;
    }
    result = result + a[n];

    if (x < (float)0.0) {
        result = PI - result;
    }
    if (y < (float)0.0) {
        result = -result;
    }
    return result;
}

AT_ITCM_SECTION_INIT(int myabs(int dat))
{
    if(dat>=0)  return dat;
    else        return -dat;
}

AT_ITCM_SECTION_INIT(float myfabs(float dat))
{
    if(dat>=0)  return dat;
    else        return -dat;
}